dont know if this is too late but here u go anyway.
if you are running a 32bit operating system, this will only see 3.2 gig of memory if you want more than this you will have to move over to a 64bit operating system and is dependent on your mother board weather yiou can add more memory.
your board accepts up to 8 gig of ram in 2gig steps, you have 4 slots in total.
hope this helped and wasnt too late.
im using windows 7 ultimate 64bit with the same motherboard as you and have no issues, dont have much time for xp any more too much crap and too old you need to move on at some stage better now than never.
I am happy using win 7 much better than vista, faster less resorces